During the ten years since this project began (in part supported by a MERIT Award from NIAAA), a construct validation network has been built that supports alcohol expectancies as an active influence on alcohol use. The bulk of this support comes from studies of childhood through late adolescence when positive expectancies and drinking increase on average. Recent national surveys suggest, however, that drinking trajectories diverge during young adulthood. Among higher-drinking individuals, some maintain elevated patterns; others decrease. Because few studies have tracked expectancies and drinking through this developmental stage, it remains unclear whether decreases in positive expectancies happen first and influence drinking decreases; whether negative drinking experiences and expectancies accrue and decrease drinking; or whether drinking decreases occur for other reasons, followed by expectancy decreases (or all three); these paths also could be reciprocal. Testing these alternatives is of theoretical and practical importance; if decreases in positive expectancies influence decreases in drinking, then understanding of how positive expectancies decrease (or negative expectancies increase) might lead to more efficient prevention and intervention methods. Based on ten years of research, it is hypothesized that this latter direction of influence is the most operative. In the next phase of this project, the relationship between expectancy change and drinking change during the developmental stage when individuals enter adulthood will be investigated. Specifically, drinking and expectancy trajectories will be monitored over the four-year period beginning at age 19 during which many drinkers reach personal drinking peaks and the majority begin a decline. To insure capture of file phenomena of interest, moderate to heavy drinking individuals will be sampled at the start of the study. Participants will be interviewed every 3 months using a 3-month follow-back procedure to permit fine-grained resolution of determinants of drinking changes (i.e., some variables will reflect daily events); detailed drinking assessment in this age range will itself advance knowledge. Advanced statistical techniques will address possible relationships between expectancies and drinking, including the influence of trajectory parameters of one variable (e.g., expectancies) on the parameters of a second variable (e.g., drinking), and whether antecedents can influence trajectory parameters of drinking (e.g., slope, intercept) through changes in expectancies; that is, "dynamic mediation." As a byproduct of these primary goals, the most detailed database yet available on the parameters of alcohol consumption in this critical young-adult life-stage will be obtained.